Furnace



Oct- 4, 193?. J. B. WILLSEA ET AL 1,880,624

FURNACE Filed Aug. 18, 1930 f 171mm TTORNE y Patented Oct. 4, 1932 T Y"E Q JASPER E. WILLsEA AND THOMAS A. KENNEDY, OE ROCHESTER, NEW YORK,AssIGNORs To WILLsnA WORKS, or ROCHESTER, NEW YORK, A CORPORATION OF NEWYORK .FURNACE Y Application filed August 18, 1930. Serial No. 476,120.

This invention relates to improvements in furnaces, and especially tothat kind of furnace used for heating foundry ovens or kilns i Y part ofwhich passes through the grate of the furnace to aid the combustion offuel thereon, and the remainder is by-passed at the front of the furnacein rear of the firing door to the re box to assist in consumingcombustible gases therein, from where it is discharged into a combustionchamber, where it is `permitted to expand before it enters th-e oven.

Still another object of the invention is to provide a furnace of thiskind constructed of two cylindrical parts, which is economical of space,and the inner walls of which are easily insulated and lined withrefractory material.

To these andother ends, the invention consists in the constructionandarrangement of parts that will appear from the following descriptionwhen read in conjunction with theaccompanying drawing, the novel fea-Vtures being pointed out in the claims Aat the end of the specification,

In the drawing:

Fig. 1 is a longitudinal vertical section of a furnace constructedaccording to one embodiment of the invention, the section being takensubstantially on line 1--1 Vof Fig. 2 looking in the ldirection of thearrows, and

Fig. '2 is la plan view of the same, the top being sectioned away toexpose the interior of the furnace. v i

Referring particularly to the drawing, in which similar referencenumerals refer to the same parts in all the figures, 1 is the fire boxof the furnace arranged beneath which is the ashV pit 2, and at its topthere box communicates with a combustion or expansion chamber 3 throughan opening or flue 4. lThe outer wall or shell 5 of the re box and ashpit is constructed of sheet or cast material,

cylindrical in form, having its axis arranged l vertically. Horizontallyarranged in this -cylinder is a grate 6 of usual or preferredconstruction which separates the fire `pot from the ash pit. The partsof the grate are Y mounted Vfor a vswinging movement, for convenience inshaking, and to this end, they have downwardly projecting arms 7connected to a link 8 lwhich extends forwardly, and

ait its forward end is connected with an arm y 9 on a shaft 10 whichextends to the outside of the furnace where it is provided with a crank11 whereby it may be manually operated inthe usual manner.

The cylindrical wall has openings in front of the ash pit and fire box,and overthese openings a metalfront 12 is secured to the cylindricalcasing by any suitable means.. This front has the usual firing and ashpit doors mounted thereon for closing the open# ings therein to the firebox and the ash pit,

and is arranged forwardly of the lire box and grate to' provide apassage 13 between the ash pit and the fireboK for a purposepresentconcrete, and lthe fire box and combustionV chamber are eachconstructed of cylindrical casings or shells which may be lined with in#sulating material such as mineral wool or asbestos, the inner surfacevof which is coated' or lined with highly refractory material, such asvitriable clay.v In lining the furnace, the insulating layer is arrangedtherein and forms or cores of substantially the length vof the shellsmay7 be arranged therein before the top is placed thereon, and thelining material in a plastic state lled in between the cores and theinsulatiomafter which the cores may be removed. To form a top, a supportof combustible material may be arranged on the lining formed as above,the top of which is spaced belowthe tops of the insulation and shellsand a cover ofthe same material formed thereon, which cover is ofsufficient thickness -ly to be described. A grating 13a is arranged A tobe self-supporting when its support is consumed. By this arrangement.,expansion-and contraction of the practically monolith refractory liningis freely permitted, due to the compressibility of the insulating layerarranged between it and the outer shell. The tops may also expand freelyagainst the insulating linings between them and the` outer shells.l Ifdesired, a layer of insulating material, such as sand, may be arrangedon the top, as shown.

The shells 5 and 15 are arranged tangential to each other, and sidewalls 2O and 21 are arranged tangential thereto, forming spaces 22 and23 which may also be filled in with refractory material, as shown. .Avfurnace thus constructed is inexpensive to build, easily lined and maybe quickly relined, is fully insulated, and occupies the minimum offloor space. f

Means are provided for forcing an air blast into the furnace. To thisend, a motor driven blower 24 is provided, which is adapted to create anair current which is conducted by means of a pipe 25 leading through thespace 23 between the shells 5 and 15to the ash pit into which it isdischarged.` It will be noted that the ash pit is substantiallycylindrical in form and the lower end `of the pipe is arranged to directthe air blast into it ina horizontal direction tangential thereto, sothat it has a whirling motion in the ashpit. Some of this air passesthrough the grate, supplying a forced Adraft and oxygen to the firethereon. The rest. of the air passes upwardly just in rear of thev front12and in rear of the ash pit and firing doors through the passage 18,and serves to keep the front of the furnace cool, and as it risesmingles with the products of combustion above the fuel on the grate inthe fire box. The air and products of combustion, owing to the largerspace above the fuel, expand therein to a cer? tain extent, which tendsto decreasepits vei locity before it is discharged into the combustionchamber 3 through the flue 4. By directing the air blast tangentiallyinto the ash pit, a substantially uniform pressure may be obtainedthroughout the area of the grate. The cooler air blast entering the firebox through the passage 13 is directed against the top of the re box,and in passing aborbs the heat radiated thereto from the open The airwhich enters the fire box from the front .of theV furnace contains afull/:supply of oxygen, someof which combines with the products ofcombustion in th-efirebox to consume some --of the combustible gasescontained therein, which process is further continued in the combustionchamber, which permits greater expansion` of the mixed air and productsof combustion discharged thereto. The mixture of air and products ofcombustion enters at the frontof the top of the combustion chamber inwhich the volume is considerably increased by expansion and thevvelocity correspondingly reduced, with the result that combustion iscompleted therein and it is exhausted into the kiln from the bottomthereof through the flue or passageway 16 at a substantially uniformtemperature, provided the pressure remains constant. The gaseous mixtureentering the oven normally contains some free oxygen, which is desirablefor the oxidization of some materials, such as linseed oil used in thepreparation of cores.

It is desired to maintain a constant uniform given temperature in theoven or kiln. To this end, a thermostatic element 28 of usual or wellknown construction is arranged in the kiln or oven and controls theelectric circuit to the motor V29 which drives the blower 24. The actionof the heat' on the thermostat breaks the circuit through the motor whenlthe temperature in the oven reaches a given maximum, and thus stops theblowerand the blast, thus reducing combustion. This also reduces theflow of heat to the oven'from the furnace, thus permitting thetemperature in the oven to vfall until a minimum temperature'is reached,when the thermostat again closes the circuit through the motor todrivethe blower, which creates the pressure for again'driving heat intothe oven, and forcing a draft through'the fire to increase combustion.

f It will be noted that the ash pit space is large in comparison to thevolume of air en- 100 tering the same, and thatthe air enters the ashpit. in a horizontal direction tangential to the ash pit walls. As aresult, the entering air at high velocity as it comes directly from theblower has a whirling motion imparted 105 thereto in the ash pit wherekit absorbs considerable heat from the walls and by radiation, andbecomes preheated before it enters the fire box through the grate', andconsequently does ynot suddenly 'chill the burning 110 fuel when itcomes in contact therewith. Ow ing to the relatively large size of theash pit, the air is permitted to expand4 therein, which reduces itsvelocity, and it enters the grate at a relatively low velocity anduniform pres- 115 sure throughout its area. By this'arrangement, thefuel consumption is uniformly distributed over the grate, and theformation of clinkers, which would reduce thevefiiciency of the fuel, isprevented.

It will? also Vbe noted that the forced air draft brings into thefurnace a large volume of air containing oxygen in excess of thatrequiredfor completely consuming the fuel in the comparatively smalllire box. A compar- 125 atively large space is provided above the firein'which gases are consumed, and ther forward movement of the volume ofmixed air and gases is delayed, causing them to c be heated to acomparatively high temperature, 13

- which temperature is maintained as they pass downwardly through thecombustion chamber to the oven. Under the forced draft, a large volumeof heated air and gases is delivered to the oven, which quickly bringsthe temperature of the atmosphere in the oven to the maximum workingtemperature and actuates the thermostat to stop the forced draft, butunder natural draft some heated gases and air continues to enter thefurnace.

When starting the oven, its atmosphere soon cools when the forced draftis stopped, due to the fact that the temperature of its contents isbelow that of its atmosphere, and the forced draft is again started.ADue to the fact that the contents of the oven contains a large amountof moisture whichmust be carried o with its atmosphere, a large volumeof heated air and gas is required to maintain al normal workingtemperature therein. A furnace constructed as herein described, havingan automatically refractory linings in said shells, a flue connectingsaid shells at a point adjacent their top, a fire boX in one of saidkshells, a grate in said fire box, an ash pit under said grate, apassageway at the front of said grate between the ash pit and the lirebox, a combustion chamber in the other of said shells, a flue controlledforced air draft, is adapted to supply such a volume` In witnesswhereof, we have hereunto signed our names.

JASPER B. WILLSEA. THOMAS A. KENNEDY.

connecting the bottom of said combustion chamber with the oven to beheated, side walls arranged tangentially to said shells and securedthereto, means arranged in one of the Y spaces formed between said sidewalls and the shells for directing an air blast to the ash pit, andrefractory material filling said spaces and around said directing means.

2. A furnace for a core oven comprising a pair of cylindrical shellsvertically arranged and tangential to each other, insulating linings ofcompressible material throughout the vertical height of said shells,refractory linings of plastic material inside and in contact with saidinsulating lining' but short of said insulating lining at the top, andtops of refractory plastic material arranged on said refractory liningwithin said insulating lining, the arrangement being such that expansionand contraction of the refractory lining is compensated for by thecompressibility of said insulating lining, a flue connecting said

